auditions

why is there never any auditions for teenage female actors? i always check for WA auditions to be involved in theatre productions and all the cast required are adults. it is so annoying as i really want to be in some plays!!!!!!! i am 17 years old and can never get any auditions. please, please could someone give me the site for perth theatre/film, etc auditions that are suitable for someone may age. sorry if i sound fed up- its coz i am.